It follows an incident in Co Armagh where police stopped a vehicle which had been fitted with lights that flashed red, green and blue.
A PSNI spokesperson said: “In this instance there was no ulterior motive other than the driver thought it looked good. It would have been extremely serious if it was being used to imitate police.
“A fixed penalty ticket and a vehicle rectification notice were issued.
“It’s up to you to ensure your vehicle is legal, silly actions can lead to serious consequences.”